From patchwork Fri Apr 3 20:31:45 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Adhemerval Zanella Netto X-Patchwork-Id: 38729 Return-Path: X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from mail-qk1-x742.google.com (mail-qk1-x742.google.com [IPv6:2607:f8b0:4864:20::742]) by sourceware.org (Postfix) with ESMTPS id AD845385DC32 for ; Fri, 3 Apr 2020 20:32:16 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org AD845385DC32 Received: by mail-qk1-x742.google.com with SMTP id k13so9564072qki.2 for ; Fri, 03 Apr 2020 13:32:16 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:subject:date:message-id:in-reply-to :references; bh=O6g044IvL9acLm9U6ag+L+YR/9NTIHJUM1xKG/cWPmE=; b=L8wH13JqiRS3RuHieC6UqR71nrfWCqlYbBIIuWGYz9hFKLfMBB4Y+f57FE/pGuDZ30 OtxSyaUuLkHzuQJ68taKQLA/oPmo+V0O42N/7mtuLCSEdoX/CgjaKE49Nl/JZBRy6iNN oL7gnyaYqtVRG/qqNBYKxYPaEJYxjpp+6l4Ngn1gt19B/N96TR06dLUpmrd3I/QoUi6l bm7AqcerOsOkoIj9WjIrd5Ym1Da2F3m2sHOPMCiEqMEEIXN8UXdA8K+90CZEM9FnWoek UKG3ra8qJY6nHqLh6OXmr61/wKYOW/baTRyq8aC9Bn6NJmAY6mTerDdRuIAaFVZZtOe4 htqw== X-Gm-Message-State: AGi0PuaxNXAiKPjCM3zMGs3glULGlR1/vRWW2LHxlV29VkWvyWGBCU7i 18rrTqVkAztJ/CvDcL/WIV/Gxtqvc6A= X-Google-Smtp-Source: APiQypLctUtqeKVYjg9gjW14dOCjpCkgr5lwWKkxCXfRHSd8NYPqYMFEN1GXznkbuNyWSv3TESJeqg== X-Received: by 2002:a37:9544:: with SMTP id x65mr10056579qkd.48.1585945935910; Fri, 03 Apr 2020 13:32:15 -0700 (PDT) Received: from localhost.localdomain ([177.194.48.209]) by smtp.googlemail.com with ESMTPSA id d141sm7063535qke.68.2020.04.03.13.32.14 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 03 Apr 2020 13:32:15 -0700 (PDT) From: Adhemerval Zanella To: libc-alpha@sourceware.org Subject: [PATCH v4 05/21] nptl: i386: Fix Race conditions in pthread cancellation [BZ#12683] Date: Fri, 3 Apr 2020 17:31:45 -0300 Message-Id: <20200403203201.7494-6-adhemerval.zanella@linaro.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200403203201.7494-1-adhemerval.zanella@linaro.org> References: <20200403203201.7494-1-adhemerval.zanella@linaro.org> X-Spam-Status: No, score=-26.5 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, KAM_SHORT, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 03 Apr 2020 20:32:18 -0000 This patch adds the i386 modifications required for the BZ#12683 fix by adding the arch-specific cancellation syscall bridge. The syscall bridge uses the old int80 instruction because by using the optimized vDSO symbol the resulting PC value for an interrupted syscall points to an adress outside the expected markers in __syscall_cancel_arch. It has been discussed in LKML [1] on how kernel could help userland to accomplish it, but afaik discussion has stalled. Also, sysenter should not be used directly by libc since its calling convention is set by the kernel depending of the underlying x86 chip (check kernel commit 30bfa7b3488bfb1bb75c9f50a5fcac1832970c60). Checked on i686-linux-gnu. [1] https://lkml.org/lkml/2016/3/8/1105 --- sysdeps/i386/nptl/tcb-offsets.sym | 3 + sysdeps/unix/sysv/linux/i386/Makefile | 2 +- sysdeps/unix/sysv/linux/i386/syscall_cancel.S | 104 ++++++++++++++++++ 3 files changed, 108 insertions(+), 1 deletion(-) create mode 100644 sysdeps/unix/sysv/linux/i386/syscall_cancel.S diff --git a/sysdeps/i386/nptl/tcb-offsets.sym b/sysdeps/i386/nptl/tcb-offsets.sym index 2ec9e787c1..2dc3bf2869 100644 --- a/sysdeps/i386/nptl/tcb-offsets.sym +++ b/sysdeps/i386/nptl/tcb-offsets.sym @@ -14,3 +14,6 @@ MUTEX_FUTEX offsetof (pthread_mutex_t, __data.__lock) POINTER_GUARD offsetof (tcbhead_t, pointer_guard) FEATURE_1_OFFSET offsetof (tcbhead_t, feature_1) SSP_BASE_OFFSET offsetof (tcbhead_t, ssp_base) + +-- Not strictly offsets, used on syscall_cancel.S +TCB_CANCELED_BITMASK CANCELED_BITMASK diff --git a/sysdeps/unix/sysv/linux/i386/Makefile b/sysdeps/unix/sysv/linux/i386/Makefile index da716e2c1b..7928497a35 100644 --- a/sysdeps/unix/sysv/linux/i386/Makefile +++ b/sysdeps/unix/sysv/linux/i386/Makefile @@ -9,7 +9,7 @@ $(objpfx)tst-bz21269: $(shared-thread-library) endif ifeq ($(subdir),elf) -sysdep-dl-routines += libc-do-syscall +sysdep-rtld_routines += libc-do-syscall sysdep-others += lddlibc4 install-bin += lddlibc4 endif diff --git a/sysdeps/unix/sysv/linux/i386/syscall_cancel.S b/sysdeps/unix/sysv/linux/i386/syscall_cancel.S new file mode 100644 index 0000000000..d2d4cfe522 --- /dev/null +++ b/sysdeps/unix/sysv/linux/i386/syscall_cancel.S @@ -0,0 +1,104 @@ +/* Cancellable syscall wrapper. Linux/i686 version. + Copyright (C) 2020 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +#include + +/* long int [eax] __syscall_cancel_arch (int *cancelhandling [SP], + long int nr [SP+4], + long int arg1 [SP+8], + long int arg2 [SP+12], + long int arg3 [SP+16], + long int arg4 [SP+20], + long int arg5 [SP+24], + long int arg6 [SP+28]) */ + +ENTRY (__syscall_cancel_arch) + pushl %ebp + cfi_def_cfa_offset (8) + cfi_offset (ebp, -8) + pushl %edi + cfi_def_cfa_offset (12) + cfi_offset (edi, -12) + pushl %esi + cfi_def_cfa_offset (16) + cfi_offset (esi, -16) + pushl %ebx + cfi_def_cfa_offset (20) + cfi_offset (ebx, -20) + + .global __syscall_cancel_arch_start +__syscall_cancel_arch_start: + + /* if (*cancelhandling & CANCELED_BITMASK) + __syscall_do_cancel() */ + testb $TCB_CANCELED_BITMASK, (%eax) + jne 1f + + /* Issue a 6 argument syscall, the nr [%eax] being the syscall + number. */ + movl 24(%esp), %eax + movl 28(%esp), %ebx + movl 32(%esp), %ecx + movl 36(%esp), %edx + movl 40(%esp), %esi + movl 44(%esp), %edi + movl 48(%esp), %ebp + + /* We can not use the vDSO helper for syscall (__kernel_vsyscall) + because the returned PC from kernel will point to the vDSO page + instead of the expected __syscall_cancel_arch_{start,end} + marks. */ + int $128 + + .global __syscall_cancel_arch_end + .type __syscall_cancel_arch_end, @function +__syscall_cancel_arch_end: + + popl %ebx + cfi_restore (ebx) + cfi_def_cfa_offset (16) + popl %esi + cfi_restore (esi) + cfi_def_cfa_offset (12) + popl %edi + cfi_restore (edi) + cfi_def_cfa_offset (8) + popl %ebp + cfi_restore (ebp) + cfi_def_cfa_offset (4) + ret + +1: + /* Although the __syscall_do_cancel do not return, we need to stack + being set correctly for unwind. */ + popl %ebx + cfi_restore (ebx) + cfi_def_cfa_offset (16) + popl %esi + cfi_restore (esi) + cfi_def_cfa_offset (12) + popl %edi + cfi_restore (edi) + cfi_def_cfa_offset (8) + popl %ebp + cfi_restore (ebp) + cfi_def_cfa_offset (4) + jmp __syscall_do_cancel + +END (__syscall_cancel_arch) +libc_hidden_def (__syscall_cancel_arch)